1. Field of the Invention
The present invention relates to an image forming apparatus that is capable of forming a multicolor image, an image forming cartridge supporter that is capable of being pulled out from the body of the image forming apparatus and supporting a plurality of image forming cartridges, and an image forming unit included in the image forming apparatus.
2. Description of the Related Art
Image forming apparatuses are known that removably include an image forming unit which removably contains a plurality of image forming cartridges.
For example, Japanese Patent Application Laid-Open (kokai) No. 4-337758 describes an image forming apparatus including a main cartridge and a plurality of sub cartridges. The main cartridge is removably attached to the body of the image forming apparatus. The main cartridge includes an image carrier on which an electrostatic latent image is formed. The sub cartridges are removably attached to the main cartridge. The sub cartridges are parts of a developing unit. Each sub cartridge includes a developer carrying member (a development roller).
In this image forming apparatus, each of the sub cartridges is electrically connected to the body of the image forming apparatus via the main cartridge. More specifically, one end of the developer carrying member is in contact with a contact member secured to a contact plate disposed on the main cartridge. Additionally, the contact plate is in contact with a contact provided to the body of the image forming apparatus. Thus, a high-voltage power supply unit provided to the body for applying a developing bias voltage is electrically connected to the developer carrying member so that the developing bias voltage is applied between the image carrier and the developer carrying member.
In the image forming apparatus having such a structure, in order to perform a reliable image forming operation, a reliable electrical connection is required between a power feeding portion (an electrical connection portion) and each of the image forming cartridges. That is, a reliable electrical connection is required between each of the image forming cartridges and the image forming cartridge supporter which is part of the frame of the image forming unit. In addition, a reliable electrical connection is required between the image forming cartridge supporter and the body of the image forming apparatus.
The amounts of consumption of the individual color developer materials are different in the image forming apparatus. Accordingly, every time the developer material of a specific color runs out, it is necessary to pull out the image forming unit from the body, take out the image forming cartridge with the developer material running out from the image forming unit, and do maintenance. To facilitate the maintenance of the image forming apparatus, the image forming cartridge and the image forming cartridge supporter need to be easily removed and mounted.